Rendered PEM electrolyser stack. Illustrative.

AWE · PEM · SOEC

Three technologies. One physics.

Alkaline, PEM and solid oxide cells age in different ways. The same electrochemistry describes all three, so one engine can read them all.

Inside the stack

Where performance is decided.

Plates, porous transport layers, catalyst layers and the membrane or separator. Each ages by its own mechanism, and each leaves its own signature in the data.

What HYDRA OS reads

Mechanisms, not just symptoms.

HYDRA OS reads the leading indicator of each mechanism, so a change is attributed to its cause rather than averaged into one stack voltage.

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Catalyst layer

Membrane

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Alkaline (AWE)

The most deployed technology at scale. Large cells and long stacks make scale-up and shunt currents the central evidence questions.

Electricity consumption, state of the art 2020: 50 kWh/kgSource note:
Degradation, state of the art 2020: 0.12%/1,000 hSource note:

Alkaline (AWE): degradation mechanisms and what HYDRA OS reads
Degradation mechanism	Consequence for the stack	Leading indicator HYDRA OS reads
Potassium hydroxide corrosion of separators and electrodes	Increasing ohmic loss; separator embrittlement	Ohmic slope change in the polarisation curve
Gas purity at low load	Crossover stays roughly constant while production falls, so the share of H₂ in O₂ rises towards the safety limit	H₂-in-O₂ concentration against load
Reverse currents during shutdown	Electrode degradation that accumulates with start/stop cycles	Activation overpotential change after shutdown events
Shunt currents through the electrolyte manifolds	Current lost to parasitic paths; uneven cell loading in long stacks	Faradaic efficiency and cell-voltage spread along the stack

PEM

Compact and responsive to fluctuating power. Membrane and anode-catalyst ageing under dynamic operation are the main evidence questions.

Electricity consumption, state of the art 2020: 55 kWh/kgSource note:
Degradation, state of the art 2020: 0.19%/1,000 hSource note:

PEM: degradation mechanisms and what HYDRA OS reads
Degradation mechanism	Consequence for the stack	Leading indicator HYDRA OS reads
Membrane thinning and pinholing under dynamic load	Rising hydrogen crossover into the oxygen stream; eventual safety trip	H₂-in-O₂ concentration rising at fixed load; fluoride emission rate in the product water
Catalyst layer delamination	Loss of active area; irreversible efficiency loss	Cell-level voltage divergence within the stack
Iridium dissolution and OER catalyst degradation	Rising anode overpotential at constant current	Voltage shift in the low-current (kinetic) region at reference conditions
Titanium PTL passivation and cation contamination of the membrane	Rising ohmic loss	Area-specific resistance (ohmic slope) at reference conditions

Solid oxide (SOEC)

High efficiency with heat integration. Thermal cycling and electrode microstructure changes dominate degradation.

Electricity consumption, state of the art 2020: 40 kWh/kgSource note:
Degradation, state of the art 2020: 1.9%/1,000 hSource note:

Solid oxide (SOEC): degradation mechanisms and what HYDRA OS reads
Degradation mechanism	Consequence for the stack	Leading indicator HYDRA OS reads
Thermal cycling stress and interconnect oxidation	Seal failure, delamination at the electrode–electrolyte interface	Degradation rate tracked against cumulative thermal cycles
Nickel migration and agglomeration in the fuel electrode	Loss of active sites and rising polarisation resistance	Polarisation resistance trend (impedance, where available)

Across all three.

Illustrative render, close-up of the membrane: water split into hydrogen and oxygen.

Degradation mechanism	Consequence for the stack	Leading indicator HYDRA OS reads
Cumulative area-specific resistance growth from combined mechanisms	Energy per kilogram of hydrogen climbs over project life, raising LCOH	Cell voltage at a fixed reference current density

AEM. Anion exchange membrane electrolysis: research.

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